Various types of disease conditions present clinical situations in which a vessel of a patient needs to be artificially supported to maintain an open passageway through which fluids, such as blood, can flow. For example, blood flow through an artery can be impeded due to a build-up of cholesterol on the interior wall of the vessel. Also, vessel walls can be weakened be a variety of conditions, such as aneurysms.
Intraluminal support frames, sometimes referred to as stents, provide an artificial mechanism to support a body vessel. Stents are typically tubular-shaped members that are placed in the lumen of the vessel and, once deployed, exert a radially-outward directed force onto the vessel wall to provide the desired support.
Stents are typically positioned at the point of treatment by navigation through the vessel, and possibly other connected vessels, until the point of treatment is reached. This navigation requires the stent to be able to move axially through the vessel(s) prior to deployment, while still maintaining the ability to exert an outward force on the interior wall once deployed. Accordingly, stents typically have radially unexpanded and expanded configurations. In the unexpanded configuration, the stent has a relatively small diameter that allows it to move axially through the vessel. In the expanded configuration, the stent has a relatively large diameter that allows it to exert an outward force on the interior wall of the lumen, thereby providing the desired support to the vessel.
During navigation through the vessel(s), the stent will likely encounter various turns and bends, which requires the stent to have a degree of longitudinal flexibility. Various stent configurations exist in the art that provide this desired flexibility to some degree. One approach utilizes a plurality of interconnected rings. The members that connect the rings provide the stent with flexibility. Unfortunately, the longitudinal flexibility can result in localized radial movement in the stent when the stent encounters a turn or bend. For example, one portion of a ring member may separate from an underlying balloon, which can interfere with navigation.